Monday brought a solid reversal to the downward movement stock market investors suffered late last week. Major market benchmarks rose between 0.5% and 0.75% as market participants chose to see the positives in comments from U.S. central bank chief Janet Yellen. Even though last week's employment report included weak job growth and falling labor participation rates, Yellen nevertheless left open at least the possibility of an interest rate increase at the Federal Reserve's June meeting. Investors were generally pleased with the prospects of a strengthening economy, but some stocks reacted badly. Among the worst performers were Sturm, Ruger , Mirati Therapeutics , and Barracuda Networks .

Sturm, Ruger finished the day down almost 7% on another bad day for gun-maker stocks more generally. Last week's latest data from the FBI's criminal background check database showed that fewer would-be buyers had gotten checks in preparation to make gun purchases, and over the weekend, analysts weighed the potential fallout from that slowing data and found further problems. In particular, BB&T Capital Markets downgraded Sturm, Ruger, citing the likelihood of lower consumer demand as weighing on the gun maker's stock in the short run. The company has fended off past challenges, however, so investors should think twice before changing their long-term hypothesis on the stock.

Mirati Therapeutics lost 44% of its value after the maker of molecularly targeted therapies to treat cancer gave its latest update on its three of its clinical programs. The company said its glesatinib treatment for non-small cell lung cancer showed encouraging results in a phase 1b trial, but episodes of diarrhea were primarily responsible for decisions to reduce or interrupt dosages of the candidate drug during the trial. Mirati is using a new formulation of the drug in phase 2 trials, but analysts from two separate companies downgraded the stock in light of concerns about the long-term promise of glesatinib. Competition might also become a factor going forward, even though most investors agree that the small company has plenty of promise if it can work through its study challenges.

Finally, Barracuda Networks lost almost 10%. The IT storage and security company received a downgrade from analysts at JMP Securities, who argued that Barracuda is in the middle of a cutthroat business in its cloud-computing focus. In light of rising competition, Barracuda might choose to look for strategic alternatives, including the potential sale of its business. Yet with no buyer becoming evident as of now, Barracuda will have to keep working to try to make the most of the business it has. The big question is whether Barracuda can capitalize on the rising success of cloud-based products like Office 365 to sell its own add-on products. If it can't, then declines like today's will make a lot more sense in the future.